SEOUL An envoy of South Korean President-elect Roh Moo-hyun arrives in Washington today to explain his policies on North Korea, amid ominous signs that the crisis involving the communist state's nuclear program is deepening.U.S. officials said Friday that satellite images showed North Korea could be moving toward making nuclear warheads, and a U.S. military commander called for more troops, bombers and ships to bolster South Korea's security.The envoy, member of parliament Chyung Dai-chul, is set to meet Secretary of State Colin L. Powell and other high-ranking U.S. officials on his four-day visit."It's a very difficult situation, so Seoul and Washington should cope with it through close coordination," Mr. Chyung said Saturday."I will deliver President-elect Roh's message on North Korea and South Korea-U.S. relations," he said. He is traveling with a delegation from Mr. Roh's transition team.Mr. Roh takes office Feb. 25, succeeding President Kim Dae-jung, who introduced South Korea's "sunshine policy" of engagement with North Korea.Mr. Roh has promised to push on with his predecessor's attempts to engage the North but, if confirmed, moves by North Korea to produce nuclear weapons would be a major test of the policy.The moves also could mark a major step in the nuclearization of northern Asia, where nuclear-armed China fears Japan might develop the weapons in response to North Korea acquiring them."I plan to discuss ways to peacefully resolve the North Korean nuclear problems through dialogue and strengthen our alliance with the United States," Mr. Chyung told KBS radio.Mr. Roh has pledged to work closely with Washington to defuse the nuclear crisis, but he seeks a more prominent role for Seoul in dealing with security issues posed by Pyongyang.YTN television said Mr. Chyung was likely to meet President Bush tomorrow and deliver Mr. Roh's message, which includes a request for an early summit with Mr. Bush.After the Washington visit, the delegation is scheduled to visit Japan from Feb. 6 to 9 and to hold talks with Japanese Prime Minister Junichiro Koizumi.U.S. spy satellites showed North Korea was moving fuel rods around a major nuclear complex, including possibly some of the 8,000 spent fuel rods that experts consider a first step in building bombs.But there was no sign that crucial reprocessing of those spent rods had begun, U.S. officials said.In another sign of the deepening crisis, the commander of U.S. forces in the Pacific has asked the Pentagon for more troops, aircraft and warships to deter any "adventure" by North Korea if the United States goes to war with Iraq.The reinforcements would include several thousand more troops to bolster the 37,000 already based in South Korea, along with B-1 and B-52 bombers, and possibly an aircraft carrier.South Korea said it had not confirmed the U.S. satellite intelligence showing North Korea was moving fuel rods around its Yongbyon nuclear complex and had not been informed of any U.S. request to augment its forces in the South.